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The pervasive issue of microplastics in aquatic environments presents a formidable challenge to traditional water treatment methodologies, including those utilizing KMnO 4 . This study pioneers advanced oxidation processes (AOPs) method aimed at improving the degradation of PE microplastics by employing a dual treatment strategy that combines KMnO 4 oxidation with UV irradiation. Detailed analysis of the surface modifications and chemical functional groups of the treated PE microplastics revealed the establishment of Mn-O-Mn linkages on their surfaces. Weight reductions of 3.9%, 4.9%, and 7.5% were observed for the KMnO 4 /UVA, KMnO 4 /UVB, and KMnO 4 /UVC treatments over seven days, respectively. The emergence of carboxyl and hydroxyl groups played a crucial role in accelerating the degradation process. Notably, the combined application of UVC rays and KMnO 4 resulted in the most effective degradation of PE microplastics observed in our study. The process significantly enhanced the formation of MnO 2 particles from KMnO 4 oxidation, with concentrations ranging from 0.036 to 0.070 mM for KMnO 4 /UVA, 0.066-0.097 mM for KMnO 4 /UVB, and 0.086-0.180 mM for KMnO 4 /UVC. Furthermore, the influence of varying pH levels, KMnO 4 concentrations, and different water sources on the degradation efficacy was investigated. The pivotal role of free radicals and reactive manganese species in promoting the degradation of PE microplastics was identified. A comparative evaluation with treatments solely utilizing KMnO 4 or UV light highlighted the enhanced effectiveness of the combined approach, demonstrating its potential as an efficient solution for reducing microplastic contamination in aquatic systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Water pollution has caused problems in coastal areas, rivers, lakes, and other important water sources around the world as a result of inappropriate waste management. Meanwhile, these pollutants are harmful to humans and aquatic life. Textile dye effluent methyl orange (MO) was used in this work for dye degradation studies employing nanocomposites. As a result, the importance of synthesizing pure ZnO and Co 3 O 4 nanoparticles with composites of ZnCo 2 O 4 (zinc cobaltite) nanorods in three various proportions (90:10, 75:25, and 50:50) is emphasized in this study. Many advanced approaches were used to assess the various features of these materials, including size and shape. Fourier transform infrared (FT-IR) spectroscopy was used to determine the vibrational modes of the materials. The absorption measurements were then carried out using UV-vis spectroscopic techniques, and the photocatalytic breakdown of MO was done under visible light irradiation. The findings revealed that pure materials were inadequate for visible light activity, resulting in decreased degradation efficiencies. Spinel cobaltite structures have potential degradation efficiency under visible light, while ZnCo 2 O 4 (50:50) catalyst has superior degradation efficiency of 59.8% over MO. The crystallite size, morphology, functional group, absorption wavelength, and band gap all play important roles in enhancing the material's photocatalytic activity under visible light. Meanwhile, ZnCo 2 O 4 spinel structures are crucial for increasing charge carriers and reducing electron-hole recombination. As a result, zinc cobaltite minerals are widely used in industrial dye degradation applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Microplastic contamination has rapidly become a serious environmental issue, threatening marine ecosystems and human health. This review aims to not only understand the distribution, impacts, and transfer mechanisms of microplastic contamination but also to explore potential solutions for mitigating its widespread impact. This review encompasses the categorisation, origins, and worldwide prevalence of microplastics and methodically navigates the complicated structure of microplastics. Understanding the sources of minute plastic particles infiltrating water bodies worldwide is critical for successful removal. The presence and accumulation of microplastics has far reaching negative impacts on various marine creatures, eventually extending its implications to human health. Microplastics are known to affect the metabolic activities and the survival of microbial communities, phytoplankton, zooplankton, and fauna present in marine environments. Moreover, these microplastics cause developmental abnormalities, endocrine disruption, and several metabolic disorders in humans. These microplastics accumulates in aquatic environments through trophic transfer mechanisms and biomagnification, thereby disrupting the delicate balance of these ecosystems. The review also addresses the tactics for minimising the widespread impact of microplastics by suggesting practical alternatives. These include increasing public awareness, fostering international cooperation, developing novel cleanup solutions, and encouraging the use of environment-friendly materials. In conclusion, this review examines the sources and prevalence of microplastic contamination in marine environment, its impacts on living organisms and ecosystems. It also proposes various sustainable strategies to mitigate the problem of microplastics pollution. Also, the current challenges associated with the mitigation of these pollutants have been discussed and addressing these challenges require immediate and collective action for restoring the balance in marine ecosystems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

In this study, biochar derived from chestnut shells was synthesized through pyrolysis at varying temperatures from 300 °C to 900 °C. The study unveiled that the pyrolysis temperature is pivotal in defining the physical and chemical attributes of biochar, notably its adsorption capabilities and its role in activating peracetic acid (PAA) for the efficient removal of acetaminophen (APAP) from aquatic environments. Notably, the biochar processed at 900 °C, referred to as CN900, demonstrated an exceptional adsorption efficiency of 55.8 mg g -1 , significantly outperforming its counterparts produced at lower temperatures (CN300, CN500, and CN700). This enhanced performance of CN900 is attributed to its increased surface area, improved micro-porosity, and a greater abundance of oxygen-containing functional groups, which are a consequence of the elevated pyrolysis temperature. These oxygen-rich functional groups, such as carbonyls, play a crucial role in facilitating the decomposition of the O-O bond in PAA, leading to the generation of reactive oxygen species (ROS) through electron transfer mechanisms. This investigation contributes to the development of sustainable and cost-effective materials for water purification, underscoring the potential of chestnut shell-derived biochar as an efficient adsorbent and catalyst for PAA activation, thereby offering a viable solution for environmental cleanup efforts., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

This study aimed to investigate bone char's physicochemical transformations through co-torrefaction and co-pyrolysis processes with biomass. Additionally, it aimed to analyze the carbon sequestration process during co-torrefaction of bone and biomass and optimize the process parameters of co-torrefaction. Finally, the study sought to evaluate the arsenic sorption capacity of both torrefied and co-torrefied bone char. Bone and biomass co-torrefaction was conducted at 175 °C-300 °C. An orthogonal array of Taguchi techniques and artificial neural networks (ANN) were employed to investigate the influence of various torrefaction parameters on carbon dioxide sequestration within torrefied bone char. A co-torrefied bone char, torrefied at a reaction temperature of 300 °C, a heating rate of 15 °C·min -1 , and mixed with 5 g m of biomass (wood dust), was selected for the arsenic (III) sorption experiment due to its elevated carbonate content. The results revealed a higher carbonate fraction (21%) in co-torrefied bone char at 300 °C compared to co-pyrolyzed bone char (500-700 °C). Taguchi and artificial neural network (ANN) analyses indicated that the relative impact of process factors on carbonate substitution in bone char followed the order of co-torrefaction temperature (38.8%) > heating rate (31.06%) > addition of wood biomass (30.1%). Co-torrefied bone chars at 300 °C exhibited a sorption capacity of approximately 3 mg g -1 , surpassing values observed for pyrolyzed bone chars at 900 °C in the literature. The findings suggest that co-torrefied bone char could serve effectively as a sorbent in filters for wastewater treatment and potentially fulfill roles such as a remediation agent, pH stabilizer, or valuable source of biofertilizer in agricultural applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

This study presents the synthesis of a novel composite catalyst, ZIF-67, doped on sodium bicarbonate-modified biochar derived from kumquat peels (ZIF-67@KSB3), for the enhanced activation of peracetic acid (PAA) in the degradation of acetaminophen (APAP) in aqueous solutions. The composite demonstrated a high degradation efficiency, achieving 94.3% elimination of APAP at an optimal condition of 200 mg L -1 catalyst dosage and 0.4 mM PAA concentration at pH 7. The degradation mechanism was elucidated, revealing that superoxide anion (O 2 •- ) played a dominant role, while singlet oxygen ( 1 O 2 ) and alkoxyl radicals (R-O • ) also contributed significantly. The degradation pathways of APAP were proposed based on LC-MS analyses and molecular electrostatic potential calculations, identifying three primary routes of transformation. Stability tests confirmed that the ZIF-67@KSB3 catalyst retained an 86% efficiency in APAP removal after five successive cycles, underscoring its durability and potential for application in pharmaceutical wastewater treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The current study aimed to assess the effectiveness of biochar formed from algae in the removal of Cr(VI) through the process of impregnating brown algae Sargassum hemiphyllum with KHCO 3 . The synthesis of KHCO 3 -activated biochar (KBAB-3), demonstrating remarkable adsorption capabilities for Cr(VI), was accomplished utilizing a mixture of brown algae and KHCO 3 in a mass ratio of 1:3, followed by calcination at a temperature of 700 °C. Based on the empirical evidence, it can be observed that KBAB-3 shown a significant ability to adsorb Cr(VI) within a range of 60-160 mg g -1 across different environmental conditions. In addition, the KBAB-3 material demonstrated the advantageous characteristic of easy separation, allowing for the continued maintenance of a high efficiency in removing Cr(VI) even after undergoing numerous cycles of reuse. In conclusion, the application of KBAB-3, a novel adsorbent, exhibits considerable prospects for effective removal of Cr(VI) from diverse water sources in the near future., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Thanh-Binh Nguyen reports financial support was provided by National Science and Technology Council., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Using bone char for contaminated wastewater treatment and soil remediation is an intriguing approach to environmental management and an environmentally friendly way of recycling waste. The bone char remediation strategy for heavy metal-polluted wastewater was primarily affected by bone char characteristics, factors of solution, and heavy metal (HM) chemistry. Therefore, the optimal parameters of HM sorption by bone char depend on the research being performed. Regarding enhancing HM immobilization by bone char, a generic strategy for determining optimal parameters and predicting outcomes is crucial. The primary objective of this research was to employ artificial neural network (ANN) technology to determine the optimal parameters via sensitivity analysis and to predict objective function through simulation. Sensitivity analysis found that for multi-metals sorption (Cd, Ni, and Zn), the order of significance for pyrolysis parameters was reaction temperature > heating rate > residence time. The primary variables for single metal sorption were solution pH, HM concentration, and pyrolysis temperature. Regarding binary sorption, the incubation parameters were evaluated in the following order: HM concentrations > solution pH > bone char mass > incubation duration. This approach can be used for further experiment design and improve the immobilization of HM by bone char for water remediation., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflicts of interest to this work. We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Emerging pollutants such as natural and manufactured chemicals, insecticides, pesticides, surfactants, and other biological agents such as personal care products, cosmetics, pharmaceuticals, and many industrial discharges hamper the aquatic environment. Nanomaterials and microplastics, among the categories of pollutants, can directly interfere with the marine ecosystem and translate into deleterious effects for humans and animals. They are either uncontrolled or poorly governed. Due to their known or suspected effects on human and environmental health, some chemicals are currently causing concern. The aquatic ecology is at risk from these toxins, which have spread worldwide. This review assesses the prevalence of emerging and hazardous pollutants that have effects on aquatic ecosystems and contaminated water bodies and their toxicity to non-target organisms. Microalgae are found to be a suitable source to remediate the above-mentioned risks. Microalgae based mitigation techniques are currently emerging approaches for all such contaminants, including the other categories that are discussed above. These studies describe the mechanism of phycoremediation, provide outrage factors that may significantly affect the efficiency of contaminants removal, and discuss the future directions and challenges of microalgal mediated remediations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Acetaminophen (Apap) is widely used and is known to form toxic haloacetamides (HAcAms) during chlorination. Metformin (Met) is a typical medication with usage much higher than that of Apap and its ubiquitous presence in the environment is known. The objective of this study was to investigate the effects of Met which contains multiple amino groups potentially joining reactions and different chlorination methods on HAcAm formation from Apap. In addition, a major drinking water treatment plant (DWTP) using the largest river in southern Taiwan was sampled to study the influence of Apap in a DWTP on the HAcAm formation. Results showed increasing dichloroacetamide (DCAcAm) molar yields of Apap at a Cl/Apap molar ratio of 5 during chlorination (0.15%) and two-step chlorination (0.03%). HAcAms were formed by the chlorine substitution of hydrogen on the methyl group in Apap followed by the cleavage of the bonding between nitrogen and aromatic. While a high Cl/Apap ratio during chlorination led to reactions between chlorine and HAcAms formed decreasing the HAcAm yields, the two-step chlorination further reduced the HAcAm formation during chlorination by a factor of 1.8-8.2. However, Met which limitedly formed HAcAms increased the DCAcAm yields of Apap by 228% at high chlorine dosages during chlorination and by 244% during two-step chlorination. In the DWTP, trichloroacetamide (TCAcAm) formation was important. The formation was positively correlated with NH 4 + , dissolved organic carbon (DOC), and specific ultraviolet absorbance (SUVA). DCAcAm dominated in the presence of Apap. The DCAcAm molar yields were 0.17%-0.27% and 0.08%-0.21% in the wet and dry seasons, respectively. The HAcAm yields of Apap in the DWTP were limitedly changed between different locations and seasons. Apap could be one important cause for HAcAm formation in a DWTP, as the presence of other pharmaceuticals such as Met possibly worsens the situation in chlorine applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

In this study, sunflower seed husk biochar prepared by ZnCl 2 -activated and hydrothermal carbonization (HZSF) was studied for its effectiveness in removing tetracycline (TC) from an aqueous solution. The physical and chemical properties of materials were characterized by different methods of surface analysis. The specific surface area of HZSF is significantly enhanced over 1200 times compared with non-modified biochar (HZSF: 1578.3 m 2 ·g -1 , SF-700: 1.3 m 2 ·g -1 ), which has an enhancement effect on the TC adsorption capacity. The HZSF showed that the Langmuir isotherm and pseudo-second-order kinetic models could properly characterize the adsorption processes. In the Langmuir isotherm model, HZSF exhibited effective adsorption performance with q max of 673.0 mg·g -1 at 298 K for 24 h. The possible mechanisms for the adsorption process were the monolayer, chemical adsorption, and the participation of strong intermolecular forces. In general, HZSF has the potential to be a useful adsorbent for the elimination of antibiotics from water-based solutions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

In recent years, the unnecessary overuse of antibiotics has increased globally, resulting in antibiotic contamination of water, which has become a significant environmental concern. This study aims to examine the adsorption behavior of antibiotics (Tetracycline TC, Ciprofloxacin CIP, Ibuprofen IBP, and Sulfamethoxazole SMX) onto H 3 PO 4 -activated sunflower seed husk biochar (PSF). The results demonstrated that H 3 PO 4 could enhance the specific surface area (378.8 m 2 /g) and create a mesoporous structure of biochar. The adsorption mechanism was investigated using kinetic models, isotherms, and thermodynamics. The maximum adsorption capacities (q max ) of TC, CIP, SMX, and IBP are 429.3, 361.6, 251.3, and 251.1 mg g -1 , respectively. The adsorption mechanism of antibiotics on PSF was governed by complex mechanisms, including chemisorption, external diffusion, and intraparticle diffusion. This research provides an environmentally friendly method for utilizing one of the agricultural wastes for the removal of a variety of antibiotics from the aquatic environment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The adsorption of Pb ions, on high-density polyethylene (PE) microplastics (MPs) with the diameter of 48-500 μm, was examined in this study. According to the Langmuir isotherm, MP of the smallest size, 48 μm, had the greatest adsorption capacity of 0.38 μmol g -1 . The mechanism of Pb ions adsorption onto PE MPs was chemical adsorption, in particular, hydrogen bonding and surface complexation. Pb adsorption onto PE particles was proceeded at a rapid rate, as predicted by the pseudo-second-order rate model (R 2  > 0.99). The PE 48 μm had the maximum adsorption capacity of 0.44 μmol g-1 (or 0.2 mol m -2 ) at pH 5. While humic acid can operate as a bridging agent, boosting heavy metal adsorption on the surface of PE MPs, fulvic acid has the reverse effect. The findings indicated that PE particles may serve as a carrier of heavy metals in the aquatic environment, posing perceived risks to the environment and public health., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

In this study, the brown algae Sargassum Hemiphyllum was used as a carbon source for synthesis of magnetic porous biochar via pyrolyzing at high temperature and and doping iron oxide particles (Fe-BAB). Cu (II) species were removed from aqueous solutions using Fe-BAB under various conditions. Fe-BAB demonstrated superior Cu (II) adsorption (105.3 mg g -1 ) compared to other biochars. On the surface of Fe-BAB, there are several oxygen-containing functional groups, such as -COOH and -OH, which are likely responsible for the excellent heavy metal removal performance. By utilizing magnet, the Fe-BAB can be conveniently separated from the solution and ready for further usage. Multi-adsorption mechanisms were responsible for Cu adsorption on Fe-BAB. Using the magnetic algal biochar for heavy metal removal is feasible due to its high adsorption efficiency and simplicity of separation., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Biochars derived from three species of algae was synthesized by impregnating the green algae Ulva Ohnoi, red algae Agardhiella subulata, and brown algae Sargassum hemiphyllum with ZnCl 2 chemical activator and employed as a long-term adsorbent for ciprofloxacin (CIP) removal from water. The results revealed that combination of brown algae and ZnCl 2 chemical activator (ZBAB) successfully produced mesoporous biochar with excellent physicochemical characteristics and gave the best CIP adsorption capacity. The ZBAB yielded a high CIP adsorption capacity (190-300 mg g -1 ) under various parameter effects (initial pH, temperature and major ions). Throughought the surface characterization techniques, the proposed adsorption mechanisms were electrostatic interaction, π-π EDA interaction, pore filling and hydrogen bonding. Moreover, not only algal biochars exhibited innovative and potential adsorbent for rapid and effective remediate pollution from water, but combination of algal biomass and ZnCl 2 activator also created renewable source of energy from biomass pyrolysis., (Copyright © 2022. Published by Elsevier Ltd.)

Eco-friendly nanocomposite aerogels were prepared as adsorbents for the removal of a model pollutant (methylene blue, MB) from water. These aerogels were comprised of hydroxyapatite (HA) nanoparticles embedded within a polymer matrix consisting of a semi-interpenetrating network of xanthan gum (XG) and polyacrylic acid (PAA). Microscopy and BET analysis showed that the aerogels formed had a nanofibrous porous microstructure with a surface area of 89 m 2 /g. Rheological analysis showed that the aerogels were viscoelastic materials whose elasticity increased with increasing HA concentration (up to 5 w/w%). The aerogels were effective at removing MB from water, exhibiting an adsorption capacity of 130 mg/g after 200 min. The binding of the MB to the aerogels was mainly attributed to hydrogen bonding and electrostatic attraction. A reusability test showed that the MB removal efficiency of over 86% was preserved after 10 cycles of adsorption-desorption. These results suggest that our nanocomposite aerogels may be useful for the efficient removal of anionic pollutants from wastewater and water supplies due to their ease of synthesis, cost-effectiveness, good mechanical properties, high thermal stability, and good adsorption performance., (Copyright © 2021. Published by Elsevier B.V.)

Colourants, micropollutants and heavy metals are regarded as the most notorious hazardous contaminants found in rivers, oceans and sewage treatment plants, with detrimental impacts on human health and environment. In recent development, algal biomass showed great potential for the synthesis of engineered algal adsorbents suitable for the adsorptive management of various pollutants. This review presents comprehensive investigations on the engineered synthesis routes focusing mainly on mechanical, thermochemical and activation processes to produce algal adsorbents. The adsorptive performances of engineered algal adsorbents are assessed in accordance with different categories of hazardous pollutants as well as in terms of their experimental and modelled adsorption capacities. Due to the unique physicochemical properties of macroalgae and microalgae in their adsorbent forms, the adsorption of hazardous pollutants was found to be highly effective, which involved different mechanisms such as physisorption, chemisorption, ion-exchange, complexation and others depending on the types of pollutants. Overall, both macroalgae and microalgae not only can be tailored into different forms of adsorbents based on the applications, their adsorption capacities are also far more superior compared to the conventional adsorbents., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In this study, biochar derived from brown algal Ascophyllum nodosum was synthesized through hydrothermal carbonization (HTC) coupling with ZnCl 2 chemical activation and applied as a sustainable adsorbent for antibiotic removal from water exemplified by ciprofloxacin (CIP). Various surface analysis techniques such as Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and zeta potential were used to clarify the surface properties of prepared biochars. The adsorption performance of biochars was investigated using batch adsorption experiments with a variety of parameters (initial pH, ionic types, temperature and water matrixes). The application of prepared biochar in CIP removal showed a good result of adsorption capacity (150-400 mg g -1 ) in different conditions. Overall, algal biochars, as a product recycled from biowaste, demonstrated a novel and promising adsorbent for effective and sustainable method for removal of antibiotics from water., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

In this study, environmentally-friendly nanocomposite hydrogels were fabricated. These hydrogels consisted of semi-interpenetrating networks of carboxymethyl cellulose (CMC) molecules grafted to polyacrylic acid (PAA), as an eco-friendly and non-toxic polymer with numerous carboxyl and hydroxyl functional groups, which were reinforced with different levels of graphene oxide particles (0.5, 1.5 or 3% wt). Field-emission electron scanning microscopy (FESEM) images indicated that the pore size of the nanocomposites decreased with increasing graphic oxide concentration. The presence of the graphic oxide increased the storage modulus and thermal stability of the nanocomposite hydrogels. The hydrogels had an adsorption capacity of 138 mg/g of a model cationic dye pollutant (methylene blue) after 250 min. Moreover, a reusability test showed that the adsorption capacity remained at around 90% after 9 cycles. Density functional theory (DFT) simulations suggested that the adsorption of methylene blue was mainly a result of π-π bonds, hydrogen bonds, and electrostatic interactions with graphene oxide. Our results indicated that the nanocomposite hydrogels fabricated in this study may be eco-friendly, stable, efficient, and reusable adsorbents for ionic pollutants in wastewater treatment., (Copyright © 2021 Elsevier B.V. All rights reserved.)

As plastics have been omnipresent in society ever since their introduction in 1907, global plastic production has ballooned in the 20th century or the Plasticene Era (Plastic Age). After their useful life span, they deliberately or accidentally, are disposed of in the environment. Influenced by different factors, plastics undergo fragmentation into microplastics (MPs) and present hazardous risks in all life forms including humans. Obliterating MPs from the environment has been a global challenge for the attainment of sustainable development goals (SDGs). This review aims to present MP degradation routes with a great focus on the thermodegradation and biodegradation routes as sustainable routes of MP degradation. These routes can achieve the reduction and obliteration of MPs in the environment, thus reducing their hazardous effects. Moreover, the thermodegradation of MPs can produce fuels that help solve the dilemma of energy security. Overall, continued research and development are still needed, however, these novel approaches and the increased awareness of the microplastics' hazards give us hope that we can achieve sustainable development in the near future., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

This study aims to investigate the adsorption behavior of cationic and anionic dyes of methylene blue (MB) and Congo red (CR) onto wet-torrefied Chlorella sp. microalgal biochar respectively, as an approach to generate a waste-derived and low-cost adsorbent. The wet-torrefied microalgal biochar possessed microporous properties with pore diameter less than 2 nm. The optimum adsorbent dosage of wet-torrefied microalgal biochar for MB and CR dyes removal were determined at 1 g/L and 2 g/L, respectively, with their natural pHs as the optimum adsorption pHs. The determined equilibrium contact times for MB and CR were 120 h and 4 h, respectively. Based on the equilibrium modeling, the results revealed that Langmuir isotherm showed the best model fit, based on the highest R 2 coefficient, for both the adsorption processes of MB and CR using the wet-torrefied microalgal biochar, indicating that the monolayer adsorption was the dominant process. From the modeling, the maximum adsorption capacities for MB and CR were 113.00 mg/g and 164.35 mg/g, respectively. The kinetic modeling indicated the adsorption rate and mechanism of the dyes adsorption processes, which could be crucial for future modeling and application of wet-torrefied microalgal biochar. From the results, it suggests that the valorization of microalgae by utilizing wet-torrefied microalgal biochar as the effective adsorbent for the removal of toxic dyes with an approach of microalgal biorefinery and value-added application to the environment is feasible., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Amine-containing pharmaceuticals formed nitrosamines that are nitrogenous disinfection byproducts of public concerns due to their carcinogenicity. The objective of this study was to investigate the co-effect of additional inorganic nitrogen in different forms (ammonium, nitrite, and nitrate) and different disinfection approaches (chlorination, monochloramination, dichloramination, and two-step chlorination) on eight nitrosamine formation from four widely used pharmaceuticals. N-nitrosodimethylamine (NDMA) was the main species formed. The presence of N-nitrosomethylethylamine (NMEA), nitrosomorpholine (NMor), and N-nitrosopiperidine (NPip) was found in certain experiments. For one-step chlorination, the influential factors, in decreasing order of importance, were the molecular structural characteristics of the pharmaceutical, oxidation method, and presence and form of additional nitrogen. In four pharmaceuticals with comparative structures, the availability of amine intermediates during degradation was the key to higher nitrosamine yields. Monochloramine significantly enhanced nitrosamine formation from four pharmaceuticals. NDMA formation by adding hypochlorous acid and ammonium separately were lower than those during monochloramination. During two-step chlorination, NDMA formation was enhanced at certain pre-chlorine doses (e.g., a Cl/N molar ratio of 20 or 4). The pre-chlorine dose changed the Cl/N ratio. As the ratio was increased, the combined chlorine residual was formed and decreased. When the ratio was high, breakpoint chlorination possibly occurred enhancing NDMA formation. While NDMA formation was successfully inhibited by two-step chlorination, ammonium brought the NDMA yields of these pharmaceuticals back to the range observed in chloramination, suggesting the importance of ammonium control for limiting NDMA formation from pharmaceuticals during two-step chlorination., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Chlorpheniramine is a pharmaceutical widely used and found in water environments. Besides hormone disruption and adverse environmental effects, chlorpheniramine forms carcinogenic nitrosamines during disinfection. We have demonstrated previously the efficient adsorption of chlorpheniramine from aqueous solution onto graphene oxide-magnetite composite (GO-Fe 3 O 4 ). The present study focused on the elimination of chlorpheniramine and the formation of nitrosamine byproducts during reaction with H 2 O 2 over GO-Fe 3 O 4 catalyst. The effects of the morphology of GO-Fe 3 O 4 in terms of iron fraction, pH, concentrations of H 2 O 2 and organic matters on chlorpheniramine removal in the GO-Fe 3 O 4 -H 2 O 2 system were investigated. Chlorpheniramine was efficiently removed at pH 9 when GO-Fe 3 O 4 had a higher micropore volume and surface area. Kinetics study showed that both oxidation (k = 5.1(±0.2) × 10 -3 (mg g -1 ) -1  min -1 ) and adsorption reactions (k = 2.7(±0.1) × 10 -3 (mg g -1 ) -1  min -1 ) fitted well with the second-order kinetics model. The adsorption sites on the GO-Fe 3 O 4 surface could be different from those involved during catalytic oxidation. Chlorpheniramine removal decreased by 44.9% in the 5th cycle without regeneration due to the structural fracture of GO-Fe 3 O 4 . A tentative pathway of chlorpheniramine degradation and nitrosamine formation by GO-Fe 3 O 4 -H 2 O 2 was proposed. GO-Fe 3 O 4 was an adsorbent and effective catalyst in chlorpheniramine degradation by H 2 O 2 that exhibited limited nitrosamine formation at moderate reaction time., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

Chlorpheniramine is a pharmaceutical pollutant and a precursor of carcinogenic nitrosamines during disinfection/oxidation. In our previous study, graphene oxide coated with magnetite (GO-Fe 3 O 4 ) was capable of removing chlorpheniramine in deionized water by adsorption. This study investigated the removal of chlorpheniramine and its nitrosamine formation potentials (FPs) by adsorption onto magnetic GO-Fe 3 O 4 , with respect to the influence by using real municipal wastewaters as the background. In the results, the adsorption performances of chlorpheniramine in wastewaters decreased in the order: GO-Fe 3 O 4 suspension > GO-Fe 3 O 4 particles > activated carbon. Chlorpheniramine adsorptions on GO-Fe 3 O 4 particles and activated carbon were reduced by using real wastewaters as the background, whereas chlorpheniramine adsorption on GO-Fe 3 O 4 suspension was enhanced due to the effects of surface charge on GO-Fe 3 O 4 and ionic strength variation in water. The fittings of adsorption isotherms indicated that the wastewater background reduced the surface heterogeneity of GO-Fe 3 O 4 suspension and improved the adsorption performance. Appreciable removal efficiencies of NDMA and other nitrosamine FPs were observed when GO-Fe 3 O 4 particles were added in real wastewaters. However, when chlorpheniramine was present in wastewaters, chlorpheniramine adsorption and degradation reaction simultaneously occurred on the surface of GO-Fe 3 O 4 , increasing NDMA and other nitrosamine FPs in wastewaters after GO-Fe 3 O 4 addition for chlorpheniramine adsorption. The assumption was further demonstrated by observing the NDMA-FP increase during chlorpheniramine adsorption on GO-Fe 3 O 4 in deionized water. GO-Fe 3 O 4 is a potential adsorbent for chlorpheniramine removal. Nevertheless, the low treatment efficiencies at high doses limit its application for nitrosamine FP adsorptions in real wastewaters.

Nitrosamines are toxic and emerging disinfection byproducts. In this study, three drinking water treatment plants (DWTPs) in southern Taiwan treating the same source water in Gaoping River with comparable technologies were selected. The objective was to evaluate the formation and fates of six nitrosamines and their formation potentials (FPs) from a surface water source to drinking water. Albeit decreased further downstream in the river, four nitrosamine-FPs were observed in the source water due to anthropogenic pollution in the upstream areas. In the DWTPs, nitrosamines were formed and NDMA was the main species. While high organic carbon concentrations indicated elevated nitrosamine-FPs in the source water, NDMA formation in the DWTPs was more positively associated with reductions of water parameters that quantify organic matters with double bonded ring structures. Although precursor removal via pre-oxidation is a viable approach to limit nitrosamine formation during post-disinfection, this study clearly indicates that a great portion of NDMA in treated water has been formed in the 1st oxidation step of drinking water treatment. The pre-oxidation simulations in the lab demonstrated the impact of pre-chlorination on nitrosamine formation. Given the limited removal in conventional treatment processes, avoiding nitrosamine-FPs in sources and/or nitrosamine formation during pre-oxidation become important issues to control the threats of nitrosamines in drinking water. Under current circumstance in which pre-oxidation is widely used to optimize the treatment effectiveness in many DWTPs, its adverse effect by forming nitrosamines needs to be carefully minimized and using technologies other than pre-chlorination (e.g., pre-ozonation) may be considered., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The objective of this study was to investigate the formation of different nitrosamines during chlorination or chloramination (chlor(am)ination) of five phenylurea herbicides (fluometuron, diuron, linuron, metobromuron, and propanil), with the effects of disinfection approaches, additional inorganic nitrogen, and reaction pH being studied. By analyzing six nitrosamines, N-nitrosodimethylamine (NDMA) and N-nitrosopyrrolidine (NPYR) formation was observed. The dimethylamine functional group was the key to determining whether a particular phenylurea herbicide was an important nitrosamine precursor, as the NDMA conversion ratio was much higher. Chlorination with ammonium or dichloramination enhanced the NDMA formation. NPYR formation from the herbicides that did not form NDMA was detected and was more vigorous during dichloramination or in the presence of either ammonium or nitrite. The NPYR formation was possibly related to the aniline molecular fragment from the phenylurea herbicides. Both NDMA and NPYR formation were higher at pH 8. Overall, the maximum nitrosamine conversions decreased in the order: fluometuron > diuron > propanil > metobromuron > linuron (up to 0.99%, 0.46%, 0.005%, 0.004%, and 0.003% molar conversion rates, respectively) during chlorination or chloramination and dichloramine > free chlorine > monochloramine (up to 0.99%, 0.41%, and 0.005% molar conversion rates, respectively) for given herbicide, chlorine, and nitrogen doses. Applying the results of this study, phenylurea herbicide concentrations ranging from several to tens of μg L(-1) will yield a NDMA concentration in drinking water above the level for a theoretical 10(-6) lifetime cancer risk. NPYR formation will increase the risk of these phenylurea herbicide concentrations to downstream water users. The true adverse environmental impacts of these phenylurea herbicides are important to emphasize given their high loadings as non-point source pollutants and their typical environmental scenarios (e.g., at neutral pH or with the co-occurrence of inorganic nitrogen), likely resulting in more efficient nitrosamine formation.

Heavy metal pollution, including chromium, zinc, arsenic, cadmium, mercury, copper, lead, and aluminum, in the largest industrial harbor in southern Taiwan was investigated. Increasing metal contamination was observed by monitoring heavy metal concentrations in seawater and sediments and estimating the enrichment factors, particularly those inside the harbor. Compared to other metal-polluted harbors worldwide, the presence of chromium in the sediments was relatively high. Excluding the background contribution, the harbor area was polluted by outflows from river mouths, wastewater discharging pipes, and point sources near industrial activities within the harbor. It is shown by principal component and cluster analyses that metal contamination was affected by a wide range of different and complex contamination mechanisms inside and outside the harbor, suggesting managing the pollution using straightforward strategies, i.e., solutions that only consider a single source or single pathway of metal emissions, is problematic., (Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.)

The influences of three important interferences (silica, phosphate, and vanadate) and the effect of different pH levels and initial arsenate concentrations on the breakthrough of arsenic in adsorptive media columns were examined by using the Rapid Small Scale Column Test with a 3 fractional factorial design. Three commercially available adsorbents used for arsenic removal (E33, GFH and Metsorb) were tested. Results indicated that GFH was more susceptible to water quality changes than Metsorb and E33 under conditions tested. GFH also adsorbed more anions than the other two media. The pH was the factor that had the most impact on the performance of the columns, followed by arsenic concentration and silica concentration. Lowering pH from 8.3 to 7.0 resulted in an increase of the mean bed volume treated until 10 μg/L arsenic breakthrough by 40, 12 and 18 thousands BV treated by GFH, E33 and Metsorb columns, respectively. However, at high silica concentration, lowering pH did not increase the performance of the media. GFH and Metsorb were more sensitive to changes in arsenic concentration at low pH than at high pH. Although vanadium and phosphate were previously reported to reduce arsenic adsorption in batch tests, in column mode with the presence of competitors, their effect was insignificant compared to that of pH, arsenic or silica under the conditions used in this study., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The aim of this study is to investigate the conditions for the removal of manganese ions from synthetic groundwater by oxidation using KMnO(4) to keep the concentration below the allowed level (0.05 mg/L). The process includes low-level aeration and addition of KMnO(4) in a Jar test system with Mn(2 + ) concentration of 0.50 mg/L, similar to that of natural groundwater in Taiwan. Different parameters such us aeration-pH, oxidant dose, and stirring speed were studied. Aeration alone was not sufficient to remove Mn(2 + ) ions completely even when the pH was increased. When a stoichiometric amount of KMnO(4) (0.96 mg/L) was used, a complete Mn(2 + ) removal was achieved within 15 min at an optimum pH of 8.0. As the amount of KMnO(4) was doubled, lower removal efficiency was obtained because the oxidant also generated manganese ions. The removal of Mn(2 + ) ions could be completed at pH 9.0 using an oxidant dose of 0.48 mg/L because Mn(2 + ) could be sorbed onto the MnO(2) particles. Finally, The MnO(2) particles were characterized using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX).